*{
  padding: 0;
  margin: 0;
}
.box{
  width: 300px;
  height: 500px;
  margin: 50px auto 0;
}
.game-board{
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
}
.game-board .title{
  margin-bottom: 20px;
}
.board{
  width: 100%;
 display: flex;
 align-items: center;
 justify-content: center;
 flex-wrap: wrap;
 border: 1px solid #999;
}
.board .row{
  width: 100%;
  height: 100px;
  display: flex;
}
.board .row button{
  flex: 1;
  border: none;
  outline: none;
  border: 1px solid #999;
  font-weight: bold;
  font-size: 34px;
}